The present invention relates in general to folders used in printing presses and, more particularly, to a folding cylinder assembly for use in a folder.
A number of folders are known in the prior art, one of which is referred to as a 3:2 folder. Such a folder is disclosed in U.S. Pat. No. 4,635,915 (herein incorporated by reference). This disclosure depicts a folding cylinder employed in a folder which introduces webs laid one over another between the folding cylinder and cutting cylinder which are disposed side by side and rotate in opposite directions to each other, cuts the webs in a section of the printed papers by cutting the webs by bringing the cutting knife in the cutting cylinder into engagement with the knife receiving member in the folding cylinder, and then folds the section of the printed papers. In what is referred to as a Collect run an inside section of the printed papers is held temporarily by pins in the folding cylinder so that the inside section wraps around the circumference of the folding cylinder and waits for an outside section of the printed papers. The outside section of the printed papers is superposed on the inside section of the printed papers and cut after the folding cylinder is rotated by a full turn, and then the superposed sections are folded together.
U.S. Pat. No. 4,635,915 discloses one type of folding cylinder and is hereby incorporated by reference as depicting the general structure and operation of one example of a prior art folding cylinder.
A number of folding cylinder designs are known in the prior art. Typically, they use a rotating cam, which in turn drives a swinging roller follower, which is connected to a shaft which drives eight parallel slider crank mechanisms. In one system a cam system uses a plate cam, in contrast, to a box cam used in other systems, (also known as the closed-track cam). The plate cam requires a spring load to maintain the swinging roller follower in contact with the cam surface. The system known as a 160 page 3:2 uses a box cam as illustrated in FIGS. 1 and 2.
The folding cylinders of the prior art have several drawbacks. More precisely, the problem is two-fold, the cams' operating environment is contaminated, and the cam loading is excessive.
A detrimental by-product of the newspaper folding process is paper dust. Paper dust is generated as the streams of newsprint are directed through the machine. More accurately, the paper is turned, folded, twisted, combined, compressed, cut, and folded again at linear velocities up to 30 mph.
Paper dust has the consistency of a fine saw dust. During a production run, this airborne contaminant is translucent. The contaminant becomes apparent as it settles, filling every inaccessible corner of the machine. This soft-to-the-touch dust is surprisingly destructive when combined with the latest lubrication system of the printing press.
The cam, the cam follower, and the cam gear are contained within a housing. This housing is descriptively named the `folding cylinder cam housing`. The cam housing is considered a major intrusion region. A door exists in which operators are able to change cam segments. The cam segments are changed as the mode of operation changes.
The current design of the cam into four segments increases the cams loads. The resulting four seams never align perfectly in assembly, creating ridges, which in turn cause load spikes, known as jerk. Finally, previous cam acceleration profiles were less than optimally chosen.
The loss of effectiveness of the cam is defined as the degradation of the cam follower to track the desired motion profile program. Friction and wear cause this degradation. The effects of wear can be correlated with industry observations of the 160 page 3:2 folder cams, with about 5 years of service. Whenever two interlocking surfaces move with relative motion to each other, wear occurs.
The present invention significantly overcomes these drawbacks in the prior art.